#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

typedef pair<int, int> PII;

void merge(vector<PII> &segs){
    vector<PII> res;
    sort(segs.begin(),segs.end());

    int st = -2e9, ed = -2e9;
    for(auto seg:segs){
        if(ed < seg.first){
            if(st != -2e9) res.push_back({st, ed});
            st = seg.first, ed = seg.second;
        }
        else ed = max(ed, seg.second);

    }
    if(st != -2e9) res.push_back({st, ed});
    segs = res;
}


int main(){
    int n;
    scanf("%d", &n);

    vector<PII> segs;
    for(int i = 0; i < n; i ++){
        int l,r;
        scanf("%d%d", &l, &r);
        segs.push_back({l,r});

    }
    merge(segs);
    cout<< segs.size() << endl;

    return 0;
}